1. Field of the Invention
The present invention relates to a machine tool having a working space in which workpieces are to be machined and which is closed off against the outside by a case in which an opening, that can be closed by at least one sliding door, is provided to give access to the working space.
2. Related Prior Art
Machine tools of this kind are known from the prior art.
The working space of such machine tools serves for machining workpieces that are, as a rule, mounted in a receptacle on a worktable. The machine tools comprise a spindle in which a tool can be selectively fitted for machining the workpieces.
The working space is closed off from the outside by a case in order to protect the environment and the operators from chips flying around in the working space and from splashing diluted soluble oil and coolant during machining of the workpieces. The case has an opening through which setting-up operations can be carried out and workpieces can be exchanged. This opening is normally closed by a door which is opened by an operator who wishes to carry out setting-up or tool-changing operations.
An operator door of that kind must meet quite a number of requirements; to begin with, opening of such a door must be possible very quickly and in a simple way. In addition, it must be ensured that the door mechanism cannot be soiled by chips flying around and splashing diluted soluble oil and coolant to such an extent that the door will get jammed and finally be blocked altogether.
Another requirement that must be met by such operator doors is that they must close off the opening very reliably so that the door area does not present a weak point in the case.
Another requirement to be met by such machine tools is that the opening must be very large to permit setting-up work and tool changes to be effected with the greatest possible ease. For, the smaller the operator door and, thus, the resulting opening, the greater the difficulties for the operator in carrying out the necessary operations inside the working space.
Another requirement, which is in opposition to the last-mentioned requirement, is that the outer dimensions of the machine tools should be as small as possible, and that the space requirements for the operator in front of the machine should also be as small as possible. This is to be seen against the background that machine tools of that kind are often part of numerically controlled machining centers where a great number of machine tools have to be arranged one beside the other and one opposite to the other, on the least possible floor space.
The operator doors known in the art are, for example, folding and hinged doors that are opened by folding or swinging them toward the top or the side. On the other hand, there have also been known sliding doors of the before-mentioned kind, which require that a corresponding space be available beside the sliding door for receiving the door elements when they are slid to the side. In the case of such sliding doors, the space available as operator opening is often less than half the total width of the machine tool. As frequently additional operating elements, etc., are to be arranged at the front of the machine tool, the remaining width of the operator opening is often as small as 1/3 of the overall width of the machine tool.
Especially in cases where telescoping, multi-layer doors or sliding doors are used, it is of disadvantage that on the one hand important mechanical input is required, while on the other hand the protection of the door mechanism from the working space is frequently so inefficient that the door mechanism may get soiled and, thus, jammed.
It is, therefore, a disadvantage of the known machine tools and the known operator doors that on the one hand the machine tools present a great width and/or the opening to be closed by the operator door is relatively narrow and in many cases has a limited height. Such machine tools are, consequently, not operator-friendly.
The before-mentioned hinged doors provide the disadvantage that their design is often very complex and that in addition such hinged doors swing into the working space where they create a risk of collision with the spindle.
If, in contrast, hinged doors are swung open to the outside, then much space is required in front of the machine tool, which is likewise regarded as a disadvantage.
Generally, it is another disadvantage of known operator doors that they frequently do not provide efficient sealing of the working space and that because of their mechanically very complex design they cannot be operated quickly and easily.